1. Field of Invention
The present invention relates to an apparatus of dynamic anti-vibration for a storage device, and more particularly, to an apparatus of dynamic anti-vibration for a storage device that actively generates a force to neutralize the vibration.
2. Related Art
With the increase of data capacity, data density is becoming higher and higher, and the reading device of the storage medium is getting more and more precise.
Take the optical drive as an example; the increase of data density has shortened the distance between the optical pickup head and the surface of an optical disk. Vibrations caused either by the unevenness of the optical disk itself during the rotation or by collision from an external force may lead to the shift of the optical pickup head, and thus the optical pickup head cannot be precisely focused on a data track that is predetermined to be read, and may even collide with the optical disk. And in a hard disk drive, the magnetic head of the hard disk drive also has the same problem, that is, it is easily collided because of vibration, and meanwhile, with the increase of the rotation speed of the disk, vibration of the hard disk drive itself further aggravates the problem.
Therefore, many anti-vibration designs have been provided. For example, in U.S. Pat. Nos. 6,883,175, 6,834,393, and 6,690,638, damping elements made of rubber materials are placed between the base board of the optical pickup head and the housing of the optical drive so as to absorb kinetic energy to dissipate the vibration. However, the design using damping elements to passively absorb or isolate the vibration is limited by the characteristics of the materials, and thus cannot completely absorb all vibration. In case that amplitude is too large or frequency is too low, the damping elements are not capable of effectively absorbing or isolating the vibrations. Moreover, nowadays, designs for both optical drives and hard disk drives tend to be of higher rotation speeds, and the frequency of eccentric vibration caused by the spindle motor is increased, rendering the effect of vibration absorption or isolation through the damping elements unsatisfactory.